Traffic noise is a major form of environmental noise pollution today in most densely populated urban areas. The noise generated from motor engines, transmission and exhaust systems of modern vehicles has been very much reduced due to various advancements in design technologies of modern automobile industry. On most highways today, tire-pavement noise has become the dominating source of traffic noise where traffic speeds is higher than about 45 km/h. The conventional dense graded asphalt pavements and portland cement concrete pavements often generate high traffic noise, and are considered to be undesirable from the consideration of traffic noise reduction. Major research and development efforts are on-going globally in search of ways in which tire-pavement noise could be reduced. One major component of tire-pavement noise is the noise reflected from the pavement surface. This is related to the sound absorption properties of pavement materials. This study examines the sound absorption characteristics of common road making materials with the aim to identify those material properties that could be changed during the pavement design phase so as to reduce tire-pavement noise. The common forms of asphalt and Portland cement concrete pavement materials are examined, along with widely used designs of porous asphalt and pervious concrete materials. Experiments were also performed to study the factors that affect the long-term noise reduction properties of the various pavement materials examined.
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